The use and application of liquid substances, such as cleaning preparations, pesticides, herbicides, fertilizers, coatings, lubricants etc., often require that the substances be diluted with a liquid, such as water, and the diluted preparation applied to a surface or introduced into a container. Typically, this is a multi-step operation that first involves the dilution process, which often requires that a concentrate and diluent be measured and placed into a container, and then that the combination be adequately mixed. The liquid mixture is then transferred by use of a transfer system to either be applied to a surface or introduced into a container. Typically, a pump functions as the motive force of the liquid mixture and is powered by an electric motor, by an internal combustion engine, or other appropriate means.
Liquid application systems are frequently encountered in the paving industry. The process of paving roads, runways, parking areas and the like with asphaltic concrete (asphalt) involves the transportation of the asphalt from the manufacturing plant to the paving site. Numerous types of vehicles are employed to transport asphalt from the manufacturing plant to the paving site. These vehicles include tandem dump trucks, tri-axle dump trucks, dump trailers, live-bottom trailers, hopper trailers, center drop trailers, double trailers, and the like. The asphalt transported by these vehicles is received “hot” so that it is in a workable condition at the paving site. To prevent the asphalt from sticking or adhering to the bed of the transportation vehicle, a lubricating type material, commonly known as an asphalt release agent, is applied to the truck bed prior to loading the asphalt.
The most common form of release agents are liquids which are sprayed, splashed, or otherwise applied to the vehicle truck beds. One common method of applying the release agent to the truck bed is by the use of a pump-up sprayer. In such applications, a measure of release agent is placed into the tank of the pumping unit, diluted as required (typically with water), agitated, and then pressurized to a sufficient air pressure to spray the bed of the truck. The spraying is conducted by the vehicle operator or personnel at the asphalt plant by controlling a wand or a nozzle to direct the flow of the spray unit. This method is somewhat ineffective in that the sprayers generally do not spray uniformly, and encounter decreasing air pressure while they are being used.
Other conventional spray units typically employ a pump to urge the diluent through the system, thereby both creating a liquid mixture including the diluent and the release agent and supplying the necessary pressure to spray the diluted release agent through an appropriate nozzle. Such units tend to suffer from a lack of control over the release agent concentration, and a lack of uniformity of application due to variability of the output pressure of the pump.
Accordingly, there is a need for a system and method of applying various liquid solutions wherein the concentration and application of the liquid solution can be controlled without the use of a pump.